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991.
992.
993.
Jean-Christophe Peyrard 《Comptes Rendus Physique》2003,4(10):1077-1082
In this paper, we propose to present the prospects for mid-term needs for infrared detectors. These needs are derived from expected evolutions in imaging techniques as well as from operational requirements. The main trends that shall allow the direct development in infrared detection are as much the pursuit of greater range, a better discrimination of targets, as the efforts to minimize cost, volume, weigh and consumption. These trends will lead to an examination of the specific needs for some kind of ‘smart’ infrared detector. Among these applications, we will investigate more deeply the technological requirements for flash and 3D imaging, hyperspectral and uncooled imaging. To cite this article: J.-C. Peyrard, C. R. Physique 4 (2003). 相似文献
994.
Chung BH Oh HJ Piao SG Sun IO Kang SH Choi SR Park HS Choi BS Choi YJ Park CW Kim YS Cho ML Yang CW 《Experimental & molecular medicine》2011,43(11):630-637
The aim of this study was to evaluate whether the Th17 and Treg cell infiltration into allograft tissue is associated with the severity of allograft dysfunction and tissue injury in acute T cell-mediated rejection (ATCMR). Seventy-one allograft tissues with biopsy-proven ATCMR were included. The biopsy specimens were immunostained for FOXP3 and IL-17. The allograft function was assessed at biopsy by measuring serum creatinine (Scr) concentration, and by applying the modified diet in renal disease (MDRD) formula, which provides the estimated glomerular filtration rate (eGFR). The severity of allograft tissue injury was assessed by calculating tissue injury scores using the Banff classification. The average numbers of infiltrating Treg and Th17 cells were 11.6 ± 12.2 cells/mm2 and 5.6 ± 8.0 cells/mm2, respectively. The average Treg/Th17 ratio was 5.6 ± 8.2. The Treg/Th17 ratio was significantly associated with allograft function (Scr and MDRD eGFR) and with the severity of interstitial injury and tubular injury (P < 0.05, all parameters). In separate analyses of the number of infiltrating Treg and Th17 cells, Th17 cell infiltration was significantly associated with allograft function and the severity of tissue injury. By contrast, Treg cell infiltration was not significantly associated with allograft dysfunction or the severity of tissue injury. The results of this study show that higher infiltration of Th17 cell compared with Treg cell is significantly associated with the severity of allograft dysfunction and tissue injury. 相似文献
995.
Active control of coupled flexural-torsional vibration in a flexible rotor-bearing system using electromagnetic actuator 总被引:1,自引:0,他引:1
Rotor-shaft systems are subject to non-uniform spin speed during start-up, coast-down or any non-stationary situation changing the spin speed suddenly, e.g., load fluctuation or sudden mass-loss like loss of a blade or a part thereof. For a flexurally and torsionally compliant rotor-shaft, the dynamics under non-uniform spin-speed shows inertial coupling among transverse and torsional coordinates through mass-unbalance and gyroscopic effect. This results into coupled transverse-torsional vibration, where torsional response consists of significant harmonic components at bisynchronous spin frequency, torsional natural frequency of the shaft, and at combination frequencies corresponding to sum and difference of spin and transverse natural frequencies and twice the transverse natural frequency of the rotor-shaft. As a result of the coupling, transverse rotor motion also influences the torsional motion. The Method of Multiple Scales (MMS) is used in this work to carry out an analysis of a simplified system to get an idea about the dominant frequencies of excitation. Results of numerical simulation are presented next to show the effectiveness and influence of actively controlling the transverse rotor motion on its torsional motion, at the dominant frequencies, with the help of non-contact electromagnetic force from an actuator. Transverse vibration control is also observed to control the torsional oscillations due to coupled nature of the problem. The Stability Limit Speed (SLS) of the system is also increased as a result of application of the active control action. Constant axial torque is observed to diminish the influence of coupling, and protect the system against torsional instability, but control action is a must to stabilize the transverse vibration of the system above SLS. 相似文献
996.
Active feedback control of stall in an axial flow fan under dynamic inflow distortion 总被引:1,自引:0,他引:1
Pramod B. SalunkheJohn Joseph A.M. Pradeep 《Experimental Thermal and Fluid Science》2011,35(6):1135-1142
This work proposes an active feedback control strategy using cross-correlation technique in a single stage axial flow fan operating under dynamic inflow distortion. Experiments were carried out under dynamic inflow distortion at the design speed with only three sensors and actuators, each. The stall inception mechanism studies under dynamic inflow distortion were carried out using 1-D continuous Morlet wavelet transform. It was observed that stall inception under co- (in the same direction of rotor rotation) and counter-rotating (in the opposite direction of rotor rotation) inflow distortion occurred through long and short length-scale disturbances, respectively. The knowledge of the nature of instabilities under dynamic inflow distortion was used to set the threshold of the correlation coefficient. It was observed that the active feedback control strategy resulted in a stall onset delay of 125 (?3.125 s) and 65 (?1.625 s) rotor revolutions under co- and counter-rotating inflow distortions, respectively. The highest delay under co-rotating inflow distortion was attributed to the substantially higher stall warning time as compared to counter-rotating inflow distortion. 相似文献
997.
Hideki Sano 《Journal of Mathematical Analysis and Applications》2011,377(2):807-816
We study the Neumann boundary stabilization problem of a coupled transport-diffusion system in the case where the observation is done at the boundary. In the recent paper of Sano and Nakagiri [H. Sano, S. Nakagiri, Stabilization of a coupled transport-diffusion system with boundary input, J. Math. Anal. Appl. 363 (2010) 57-72], we treated the stabilization problem for the case with Neumann boundary control and distributed observation. The novelty of this paper is the formulation of the boundary observation equation in a Hilbert space. We have an interesting result of its being expressed by using an -bounded operator with . Moreover, it is shown that a reduced-order model with a finite-dimensional state variable is controllable and observable. This means that one can always construct a finite-dimensional stabilizing controller for the original infinite-dimensional system by using a residual mode filter (RMF) approach. 相似文献
998.
The Friedel-Crafts acylation of electron-rich arenes (ferrocene and pyrene) with N-hydroxysuccinimidyl, 2,3,5,6-tetrafluorophenyl and phenyl esters of benzoic and p-methoxybenzoic acid, activated by superacidic trifluoromethanesulfonic acid is reported. The reactive acylating intermediate in this system is presumably an acyl triflate or its protonated form. 相似文献
999.
Masashi Kato 《Applied Acoustics》2011,(10):732-736
Conventional active noise control (ANC) in ducts has been realized with digital signal processing. The physical size of the conventional ANC systems is usually large owing to the signal processing interval, and the cost of the system depends on the price of the digital signal processor (DSP). This paper proposes a new ANC system with an analog neural network circuit, which will process signals in short time periods without DSP. The proposed neural network circuit has a simple structure consisting of analog multipliers and an integrator, and we simulated the performance of the circuit by HSPICE. We also fabricated a circuit connected to a real duct and confirmed operation of the proposed ANC system. 相似文献
1000.
Variable step-size based method for acoustic feedback modeling and neutralization in active noise control systems 总被引:1,自引:0,他引:1
This paper investigates the issue of the acoustic feedback during online operation of active noise control (ANC) systems. In the existing approach, two FIR filters are used for this task: adaptive for feedback path modeling (FBPM) and fixed for feedback neutralization (FBN). Previously, a simplified method is proposed where these two tasks of modeling and neutralization have been combined into one feedback path modeling and neutralization (FBPMN) adaptive filter. Here we introduce an intuition based variable step size (VSS) parameter, for LMS equation of FBPMN filter. This VSS is motivated from the fact that the error signal of FBPMN filter contains a disturbance-component that is decreasing in nature. The computer simulations are carried out for single-channel and multichannel ANC systems. It is demonstrated that the proposed method achieves better performance than the existing methods. 相似文献